linux-kernel - Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable

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Message-ID: <56EAB756.1050805@linaro.org>
Date:	Thu, 17 Mar 2016 06:55:34 -0700
From:	Steve Muckle <steve.muckle@...aro.org>
To:	Juri Lelli <Juri.Lelli@....com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Michael Turquette <mturquette@...libre.com>, rjw@...ysocki.net,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	morten.rasmussen@....com, dietmar.eggemann@....com,
	vincent.guittot@...aro.org,
	Michael Turquette <mturquette+renesas@...libre.com>,
	Patrick Bellasi <patrick.bellasi@....com>
Subject: Re: [PATCH 4/8] cpufreq/schedutil: sysfs capacity margin tunable

On 03/17/2016 02:40 AM, Juri Lelli wrote:
>> Could the default schedtune value not serve as the out of the box margin?
>>
> I'm not sure I understand you here. For me schedtune should be disabled
> by default, so I'd say that it doesn't introduce any additional margin
> by default. But we still need a margin to make the governor work without
> schedtune in the mix.

Why not have schedtune be enabled always, and use it to add the margin?
It seems like it'd simplify things.

I haven't looked at the schedtune code at all so I don't know whether
this makes sense given its current implementation. But conceptually I
don't know why we'd need or want one margin in schedutil which will be
tunable, and then another mechanism for tuning as well.